<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <title>来聊天吧！</title>
</head>
<body>
    Welcome<br/>
    <input id="text" type="text"/>
         <button onclick="send()">发送消息</button>
    <hr/>
        聊天昵称<input id="username" type="text"/>
        <button onclick="onOpenWebSocket()">WebSocket连接</button>
        <button onclick="closeWebSocket()">关闭WebSocket连接</button>
    <hr/>
    <div id="message"></div>
</body>

<script type="text/javascript">
    var websocket = null;
    var username = null;
    var http = window.location.host;
    function onOpenWebSocket() {
        //判断是否取昵称
        username = document.getElementById("username").value;
        if(username == null || username == ""){
            alert("请填写昵称！");
            return;
        }
        //判断当前浏览器是否支持WebSocket
        if ('WebSocket' in window) {
            websocket = new WebSocket("ws://"+http+"/webSocket?username="+ username);
        } else {
            alert('当前浏览器 Not support webSocket')
        }

        /**
         * 连接发生错误的回调方法
         */
        websocket.onerror = function () {
            setMessageInnerHTML("WebSocket连接发生错误");
        };

        /**
         * 连接成功建立的回调方法
         */
        websocket.onopen = function () {
            setMessageInnerHTML("WebSocket连接成功");
        }

        /**
         * 接收到消息的回调方法
         * @param event
         */
        websocket.onmessage = function (event) {
            setMessageInnerHTML(event.data);
        }

        /**
         * 连接关闭的回调方法
         */
        websocket.onclose = function () {
            setMessageInnerHTML("WebSocket连接关闭");
        }

        /**
         * 监听窗口关闭事件，当窗口关闭时，主动去关闭websocket连接，防止连接还没断开就关闭窗口，server端会抛异常。
         */
        window.onbeforeunload = function () {
            closeWebSocket();
        }
    }



    /**
     * 将消息显示在网页上
     * @param innerHTML
     */
    function setMessageInnerHTML(innerHTML) {
        document.getElementById('message').innerHTML += innerHTML + '<br/>';
    }

    /**
     * 关闭WebSocket连接
     */
    function closeWebSocket() {
        websocket.close();
    }

    /**
     * 发送消息
     */
    function send() {
        var message = document.getElementById('text').value;
        websocket.send(message);
    }
</script>
</html>